#include <bits/stdc++.h>
using namespace std;
using ll = long long;
using ull = unsigned long long;
constexpr int MOD = 998244353;
#define rep(i, n) for (int i = 0; i < (int)(n); i++)
#define rep2(i, l, r) for (int i = (l); i < (int)(r); i++)
#define all(v) v.begin(), v.end()
int main() {
  ios::sync_with_stdio(false);
  cin.tie(nullptr);
  ull N;
  cin>>N;
  ull N1=N+1;
  if(N%2==0)N/=2;
  if(N1%2==0)N1/=2;
  cout<<N*N1<<'\n';
}